P1- How do you ensure that SnCl2 is adsorbed on the optical fiber?

P2- you should wash and let the fiber dry before changing the solution. so that physisorbed species willbe removed.

P3- You shouldn't keep for 2 hrs in 3rd solution. 

P4- You might change the plating solution and use different bath.

Hello Sujoy,

Thanks for your reply.

1. How should I make sure that it's adsorbed?

2. Should I let the adsorbed species dry before rinsing the, between solutions"

3. I read the plating thickness depends on the time. Isn't it?

4. Which bath do you suggest?

1. It will depend on your fiber's charge.

2. No. After taking out from the solution, it should be rinsed with water. Then it should be dipped into solution at drying condition.

3. Not always. Here, thickness doesn't depend on time. 

4. HCHO-free bath could be another choice.

The fiber is neutral. It's not charged.

So you could characterize the fiber (microscopy /spectroscopy) after getting the Pd NPs on it, which ensure you about the SnCl2 adsorption.

Hi Raghavender Reddy Jakka ,

May I know what is your anode?

Hello Rosley,

I am assuming that by anode you meant reducing agent, as it is electroless plating. I am using formalin (37% formaldehyde) as a reducing agent.

Sujoy Sarkar,

Should I let the fiber dry after taking out from solution 1 and before rinsing it?

Hello Raghavender Reddy Jakka,

What type of material is your optical fiber and do you know if it is treated with some auxiliary agents on its surface which at first have to be removed?

Maybe acetone alone is not sufficient as a pretreatment for your purpose?

Hello Wolfgang knoll,

It is a Silicon fiber. I removed the polymer coating by placing it in acetone for 15 minutes.

Hello Raghavender Reddy Jakka,

my experience with silicon is little, but I would try after your acetone treatment a short activation step in a  bath containing ammonium hydrogen fluoride 5% solution for a few seconds or in a 10% KOH solution for a few minutes.

Wolfgang,

I think the Sn and Pd are not being adsorbed by the silicon fiber. Does these ammonium hydrogen fluoride and KOH solution increase the adsorption?

Raghavender,

as you know HF and fluorides in acidic solution are able to etch glass and silicon surfaces producing SiF4 which hydrolizes in presence of water to SiO2. This reaction is quite fast, so you have to do some trials before to find out the best way to your desired surface.

Treatment with KOH is for the same purpose but requires much more time, maybe some oxidizers are necessary additionally.

Anyway, if it does not play a role to have a Si or a SiO2 surface as substrate, I can imagine that a more or less rough surface improves absorption of Sn and Pd. Maybe you should have a look to some literature concerning etching of silicon surfaces to find some further ways to a better adhesion of your Sn and Pd.

Care of with acétone:it may contain some greasy compounds .(see B.J.Hazzard,ORGANICUM in the reagent appendix for purification of aceton,or https://www.iupac.org/publications/pac-2007/1986/pdf/5811x1535.pdf, or

http://www.lookchem.com/Chempedia/Chemical-Technology/Laboratory-Chemical-Technology/8002.html

Thanks for your answers. I followed a process mentioned in a paper and got a thin layer of copper on fiber.

The procedure is as follows

Ultrasonic cleaning - RT - 2mins

Alkaline degreasing - 60C - 5mins

Acid dipping - RT - 1mn

[

Sensitization (Solution 1) - RT - 1min

Activation (Solution 2) - RT - 1min

] - 3 times

Methanol - RT - 1min

Plating (solution 3) -60C - 60mins

RT - room temp

I used SP degreaser from caswell for degreasing and 98% H2SO4 for acid dipping.